I have come to believe that if two people are prepared to make a lifetime commitment to love and care for each other in good times and in bad, the government shouldn’t deny them the opportunity to get married.

That isn’t how I’ve always felt. As a congressman, and more recently as a senator, I opposed marriage for same-sex couples. Then something happened that led me to think through my position in a much deeper way.

In a statement, Human Rights Campaign President Chad Griffin praises Portman's new stance.

“Like countless dads across the country, Senator Portman has made the basic and courageous choice to put parenting before politics," writes Griffin. "When it comes to marriage equality, all Americans are on the same journey toward recognizing our common humanity. But while 8 in 10 Americans know a gay or lesbian person, it still takes unique courage to speak out publicly for equality. We are very grateful to Senator Portman for his virtuous stand in support of this civil rights cause.”